Compositions and methods for separating tissue

ABSTRACT

In one aspect, methods for separating biological tissue are described herein. In some embodiments, a method for separating tissue comprises providing a first composition comprising a polymerizable material, providing a second composition comprising a polymerization initiator, disposing the first composition at a first site beneath a first tissue layer, disposing the second composition at the first site, polymerizing the polymerizable material at the first site, and separating the first tissue layer from a second tissue layer.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority pursuant to 35 U.S.C. §119(e) to U.S.Provisional Patent Application Ser. No. 61/454,766, filed on Mar. 21,2011, which is hereby incorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

This invention was made with government support under CAREER awardcontract 0954109 awarded by the National Science Foundation (NSF), R21award contract EB009795 awarded by the National Institute of BiomedicalImaging and Bioengineering (NIBIB), and R01 award contract1R01EB012575-01A1 awarded by the NIBIB. The government has certainrights in the invention.

FIELD

This invention relates to compositions, systems, and methods forseparating tissue, and, in particular, to endoscopic mucosal resection(EMR) and endoscopic submucosal dissection (ESD).

BACKGROUND

Gastrointestinal (GI) cancers account for many new cases of cancerreported each year. It is estimated that over 25% of all cancers are GIrelated, with a majority of these occurring in the stomach and colon.Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection(ESD) are acknowledged as minimally invasive methods of removingdysplasias and early cancers confined to the mucosal or submucosallayers of the GI tract. However, EMR and ESD have been associated withcomplications due to coincidental damage to underlying muscle layers,such as perforation and hemorrhaging.

To reduce these risks, a solution can be injected beneath the site ofinterest to physically separate diseased tissue from the underlyingmuscalaris propria before resection. However, prior injection materialsfor endoscopic resection are limited by small mucosal lift heights,short mucosal lift durations, high costs, complex preparatoryrequirements, administration difficulties, and/or localized tissueinflammation.

SUMMARY

In one aspect, methods for separating biological tissue are describedherein. In some embodiments, a method for separating tissue comprisesproviding a first composition comprising a polymerizable material,providing a second composition comprising a polymerization initiator,disposing the first composition at a first site beneath a first tissuelayer, disposing the second composition at the first site, polymerizingthe polymerizable material at the first site, and separating the firsttissue layer from a second tissue layer. In some embodiments,polymerizing the polymerizable material comprises cross linking thepolymerizable material. In some embodiments, polymerizing thepolymerizable material comprises forming a gel. Moreover, in someembodiments, the separation of the first and second tissue layers is atleast partially caused by the polymerization of the polymerizablematerial at the first site.

Further, separating the first and second tissue layers, in someembodiments, comprises providing a gas between the first and secondtissue layers. In some embodiments, the separation of the first andsecond tissue layers is at least partially caused by the presence of thegas.

In addition, in some embodiments, a method described herein furthercomprises maintaining separation of the first and second tissue layersfor a therapeutically effective period of time. Further, in someembodiments, a method described herein further comprises removing atleast a portion of the first tissue layer from the body.

In some embodiments, a method described herein further comprisesdegrading a polymerizable material and/or a polymerization product ofthe polymerizable material. Degrading, in some embodiments, comprisesbiodegrading.

In some embodiments, a method described herein further comprisesdispensing a drug into a tissue layer from a composition or geldescribed herein. In some embodiments, a method described herein furthercomprises dispensing an imaging agent into a tissue layer from acomposition or gel described herein.

In another aspect, systems for use in tissue separation applications aredescribed herein. Tissue separation applications, in some embodiments,include endoscopic resection applications such as EMR and ESD, includinginjection-assisted EMR and ESD. In some embodiments, a system for use intissue separation applications comprises a first composition comprisinga polymerizable material, a second composition comprising apolymerization initiator, and an endoscopic device. The secondcomposition, in some embodiments, further comprises a gas foaming agent.

In another aspect, methods for displacing soft biological tissue aredescribed herein. In some embodiments, a method for displacing softtissue comprises providing a first composition comprising apolymerizable material, providing a second composition comprising apolymerization initiator, disposing the first composition at a firstsite within a first soft tissue, disposing the second composition at thefirst site, polymerizing the polymerizable material at the first site,and displacing the first soft tissue.

In another aspect, systems for use in tissue displacement applicationsare described herein. Tissue displacement applications, in someembodiments, include cosmetics applications such as anti-wrinkleapplications and lip-plumping applications. In some embodiments, asystem for use in tissue displacement applications comprises a firstcomposition comprising a polymerizable material, a second compositioncomprising a polymerization initiator, and an injection device.

These and other embodiments are described in greater detail in thedetailed description which follows.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a method for separating tissue according to oneembodiment described herein.

FIG. 2 illustrates the experimental set up for a test procedure used tomeasure the injection pressure of a composition according to oneembodiment described herein.

FIG. 3 is a graph showing the total volume expansion associated with theformation of a series of gels provided according to some embodiments ofmethods described herein.

FIG. 4 illustrates the drug delivery profile associated with a series ofgels provided according to some embodiments of methods described herein.

FIG. 5 is a series of photographs of the mucosal elevation provided byone embodiment of a method described herein compared to other methods.

FIG. 6 is a graph illustrating mucosal elevation height as a function oftime for the methods of FIG. 5.

FIG. 7 is a graph illustrating mucosal elevation height as a function oftime provided by one embodiment of a method described herein compared toother methods.

DETAILED DESCRIPTION

Embodiments described herein can be understood more readily by referenceto the following detailed description, examples, and drawings. Elements,apparatus, and methods described herein, however, are not limited to thespecific embodiments presented in the detailed description, examples,and drawings. It should be recognized that these embodiments are merelyillustrative of the principles of the present invention. Numerousmodifications and adaptations will be readily apparent to those of skillin the art without departing from the spirit and scope of the invention.

In addition, all ranges disclosed herein are to be understood toencompass any and all subranges subsumed therein. For example, a statedrange of “1.0 to 10.0” should be considered to include any and allsubranges beginning with a minimum value of 1.0 or more and ending witha maximum value of 10.0 or less, e.g., 1.0 to 5.3, or 4.7 to 10.0, or3.6 to 7.9.

I. Methods for Separating Tissue

In one aspect, methods for separating biological tissue are describedherein. In some embodiments, a method for separating tissue comprisesproviding a first composition comprising a polymerizable material,providing a second composition comprising a polymerization initiator,disposing the first composition at a first site beneath a first tissuelayer, and disposing the second composition at the first site. The firstsite, in some embodiments, comprises an interfacial region between afirst tissue layer and a second tissue layer, including an interfacialregion between two differing tissue types. Moreover, in someembodiments, the first composition further comprises a cross linker. Insome embodiments, the second composition further comprises a gas foamingagent. In some embodiments, the first composition and/or the secondcomposition further comprises a drug and/or an imaging agent.

In addition, a method described herein further comprises polymerizingthe polymerizable material at the first site. Moreover, in someembodiments, polymerization occurs only or primarily at the first site.Polymerizing the polymerizable material at the first site, in someembodiments, permits additional control of the time and place of tissueseparation. Further, in some embodiments, polymerizing the polymerizablematerial after disposing the material beneath a first tissue layer canavoid undesirable events, such as clogging of an endoscopic needle priorto disposition of the polymerizable material beneath the first tissuelayer.

In addition, in some embodiments, the polymerization of a polymerizablematerial described herein is initiated by combining the firstcomposition with the second composition. In particular, in someembodiments, polymerization is initiated by combining a polymerizablematerial of the first composition with a polymerization initiator of thesecond composition.

Further, in some embodiments described herein, polymerizing apolymerizable material comprises cross linking the polymerizablematerial. Cross linking, in some embodiments, is facilitated by a crosslinker of the first composition. A cross linker, in some embodiments, isoperable to cross link a polymerizable material to provide a polymernetwork. In other embodiments, a polymerizable material can undergocross linking without the need for an additional cross linker.

In some embodiments, polymerizing a polymerizable material comprisesforming a gel. A gel, in some embodiments, comprises a continuous phaseformed from a cross linked polymerizable material. In other embodiments,a gel comprises a discontinuous phase formed from a cross linkedpolymerizable material. In some embodiments, a gel comprises a hydrogel.A hydrogel, in some embodiments, comprises an aqueous continuous phaseand a polymeric disperse or discontinuous phase.

Further, in some embodiments, polymerizing a polymerizable material doesnot comprise photo-polymerizing or thermo-polymerizing the material.Therefore, in some embodiments, polymerizing a polymerizable materialdoes not require the use of additional equipment, such as an ultraviolet(UV) light source.

A gel comprising a cross linked polymerizable material described herein,in some embodiments, exhibits desirable biological, mechanical, and/orelectrical properties. For instance, in some embodiments, a geldescribed herein is biodegradable. A biodegradable gel, in someembodiments, degrades in vivo to non-toxic components which can becleared from the body by ordinary biological processes. In someembodiments, a biodegradable gel described herein completely orsubstantially completely degrades in vivo over the course of about 4weeks or less. Further, in some embodiments, a gel described herein isbiocompatible or cytocompatible. A biocompatible or cytocompatible gel,in some embodiments, is non-toxic and does not cause substantial tissueinflammation.

Moreover, the biodegradability and/or biocompatiblity of a gel describedherein, in some embodiments, can be tuned by altering one or more of thecomponents of a first and/or second composition described herein. Forexample, in some embodiments, the biodegradability or biocompatibilityof a gel can be altered based on the identity and/or amount of one ormore of a polymerizable material, cross linker, and polymerizationinitiator described herein.

Further, in some embodiments, a gel described herein is a strong butsoft gel. In some embodiments, for instance, a gel described herein iselastomeric. In some embodiments, a gel described herein has a highcompressive peak stress and a low initial modulus. For example, in someembodiments, a gel has a compressive peak stress of up to about 20 kPawhen measured as described hereinbelow. In some embodiments, a gel has acompressive peak stress of up to about 10 kPa. In some embodiments, agel has a compressive peak stress between about 0.5 kPa and about 20kPa, between about 1 kPa and about 15 kPa, between about 3 kPa and about12 kPa, or between about 5 kPa and about 10 kPa when measured asdescribed hereinbelow. Moreover, in some embodiments, a gel has aninitial modulus of up to about 10 kPa. When measured as describedhereinbelow. In some embodiments, a gel has an initial modulus of up toabout 5 kPa. In some embodiments, a gel has an initial modulus betweenabout 0.5 kPa and about 10 kPa, between about 1 kPa and about 9 kPa,between about 1 kPa and about 5 kPa, or between about 3 kPa and about 5kPa when measured as described hereinbelow.

In addition, in some embodiments, the mechanical properties of a geldescribed herein can be tuned by altering one or more of the componentsof a first and/or second composition described herein. For example, insome embodiments, the mechanical properties can be altered based on theidentity and/or amount of one or more of a polymerizable material, crosslinker, and polymerization initiator described herein. Therefore, thestrength and softness of a gel described herein, in some embodiments,can be tuned to fit a specific application.

Moreover, in some embodiments, a gel described herein has a highelectrical resistance. A high electrical resistance, in someembodiments, improves the performance of electrosurgery, such aselectrocautery of diseased tissue, by increasing impedance and/or heatdissipation. Further, in some embodiments, the electrical properties ofa gel described herein can be tuned by altering one or more of thecomponents of a first and/or second composition described herein. Forexample, in some embodiments, the electrical properties can be alteredbased on the identity and/or amount of one or more of a polymerizablematerial, cross linker, and polymerization initiator described herein.

In addition, in some embodiments, a gel described herein has a tunablegel point or gel setting time. A gel point or gel setting time, in someembodiments, corresponds to the cross-over of viscous and elastic moduliof the gel in rheology measurements carried out as described herein. Insome embodiments, a gel described herein has a short gel point or gelsetting time. Rapid gel setting, in some embodiments, permits more rapidtissue separation and/or resection procedures, such as endoscopicresection procedures. In other embodiments, a gel has a long gel pointor gel setting time. Less rapid gel setting, in some embodiments, canfacilitate additional or longer procedures, such as additionalpreparation and/or treatment procedures. In some embodiments, a gel hasa gel setting time of less than about 10 minutes. In some embodiments, agel has a gel setting time of less than about 5 minutes or less thanabout 4 minutes. In some embodiments, a gel has a gel setting timebetween about 1 minute and about 30 minutes, between about 1 minute andabout 10 minutes, or between about 1 minute and about 5 minutes.

Moreover, the gel point or gel setting time of a gel described herein,in some embodiments, can be tuned by altering one or more of thecomponents of a first and/or second composition described herein. Forexample, in some embodiments, the gel point or gel setting time can bealtered based on the identity and/or amount of one or more of apolymerizable material, cross linker, and polymerization initiatordescribed herein.

In addition, in some embodiments described herein, forming a gelcomprises expanding the total volume of a material, such as acombination of first and second compositions described herein. In someembodiments, forming a gel comprises expanding a total volume by up toabout 200%. In some embodiments, forming a gel comprises expanding atotal volume by up to about 100%. In some embodiments, a total volumeexpansion is between about 1% and about 90%, between about 5% and about80%, between about 10% and about 90%, between about 15% and about 85%,or between about 30% and about 80%. Further, in some embodiments, atotal volume expansion is time-dependent. For example, in someembodiments, the volume expansion increases with time after combinationof the first and second compositions at a first site described herein.Further, in some embodiments, the volume expansion at least partiallycauses the separation of a first and second tissue layer describedherein.

Moreover, the expansion volume of a gel described herein, in someembodiments, can be tuned by altering one or more of the components of afirst and/or second composition described herein. For example, in someembodiments, the total expansion volume can be altered based on theidentity and/or amount of one or more of a polymerizable material, crosslinker, polymerization initiator, and gas foaming agent describedherein.

In addition, a method described herein further comprises separating thefirst tissue layer from a second tissue layer. In some embodiments, thefirst tissue layer and the second tissue layer are immediately adjacentlayers. In other embodiments, the first tissue layer and the secondtissue layer are not immediately adjacent layers. Separating a firsttissue layer from a second tissue layer, in some embodiments, isfacilitated by disposing the first and second compositions at a firstsite comprising an interfacial region between the first and secondtissue layers. Moreover, separating a first tissue layer from a secondtissue layer, in some embodiments, comprises forming a gap between thetissue layers. In some embodiments, separating a first tissue layer froma second tissue layer comprises increasing a gap or distance between thetissue layers.

Further, separating a first tissue layer from a second tissue layer, insome embodiments, comprises forming a gap between the tissue layers ofat least about 1 mm. In some embodiments, separating a first tissuelayer from a second tissue layer comprises forming a gap between thetissue layers of at least about 5 mm or at least about 10 mm. In someembodiments, separating a first tissue layer from a second tissue layercomprises forming a gap between the tissue layers of about 1 mm to about10 mm, about 3 mm to about 10 mm, about 4 mm to about 10 mm, about 5 mmto about 8 mm, or about 5 mm to about 10 mm.

Moreover, in some embodiments, separation between a first tissue layerand a second tissue layer is at least partially provided by polymerizinga polymerizable material as described herein. For instance, in someembodiments, separation between a first tissue layer and a second tissuelayer is provided by forming a gel. In some embodiments, separationbetween a first tissue layer and a second tissue layer is provided by agas. In some embodiments, for example, separating a first tissue layerfrom a second tissue layer comprises providing a gas between the firstand second tissue layers. A gas, in some embodiments, is provided by agas foaming agent of a second composition described herein. A gasfoaming agent, in some embodiments, is operable to produce a gas whencombined with a first composition described herein. For example, in someembodiments, a gas foaming agent is operable to produce a gas whencombined with an acidic first composition. In addition, in someembodiments, the amount of tissue separation can be altered based on theidentity and/or amount of a gas foaming agent described herein.

Further, a first tissue layer and/or a second tissue layer describedherein, in some embodiments, comprises soft tissue. In some embodiments,a first tissue layer and/or a second tissue layer comprisesgastrointestinal (GI) tissue, such as GI mucosal, submucosal, or muscletissue. Moreover, in some embodiments, neither a first tissue layer nora second tissue layer comprises hard tissue, such as bone tissue ortooth tissue. In addition, in some embodiments, a first tissue layer anda second tissue layer comprise differing tissues. For instance, in someembodiments, a first tissue layer comprises mucosal or submucosal tissueand a second tissue layer comprises muscle tissue. In some embodiments,a first tissue layer comprises diseased tissue and a second tissue layercomprises healthy tissue. Diseased tissue, in some embodiments,comprises cancerous tissue or a lesion.

In some embodiments, separating a first tissue layer from a secondtissue layer comprises elevating the height or lift of a mucosal orsubmucosal layer. Further, the initial mucosal or submucosal height orlift elevation, in some embodiments, is between about 1 mm and about 10mm. In some embodiments, the initial elevation is between about 3 mm andabout 10 mm, between about 4 mm and about 10 mm, between about 5 mm andabout 8 mm, or between about 5 mm and about 10 mm. In some embodiments,the initial elevation is greater than that produced by saline. Further,in some embodiments, the initial elevation can be tuned by altering oneor more of the components of a first and/or second composition describedherein. For example, in some embodiments, the initial elevation can bealtered based on the identity and/or amount of one or more of apolymerizable material, cross linker, and polymerization initiatordescribed herein.

In addition, in some embodiments, a method described herein furthercomprises maintaining separation of the first and second tissue layersat a desired distance for a therapeutically effective period of time. Insome embodiments, for example, a method comprises maintaining aseparation of the first and second tissue layers for a time periodsufficient to carry out endoscopic resection, including resection ofdiseased tissue. In some embodiments, a method comprises maintaining atleast about 90% or at least about 80% of an initial tissue separationfor over 1 hour. In some embodiments, a method comprises maintaining atleast about 90% or at least about 80% of the initial tissue separationfor a duration of about 1 minute to about 2 hours.

In some embodiments, a method comprises maintaining a tissue separationof at least about 1 mm for at least about 1 hour. In some embodiments, amethod comprises maintaining a tissue separation of at least about 5 mmor at least about 10 mm for at least about 1 hour or at least about 2hours. In some embodiments, a method comprises maintaining a tissueseparation of about 1 mm to about 10 mm or about 5 mm to about 10 mm forabout 1 minute to about 2 hours. In some embodiments, a method comprisesmaintaining a tissue separation of about 1 mm to about 10 mm or about 5mm to about 10 mm for about 3 minutes to about 10 minutes, about 10minutes to about 2 hours, about 30 minutes to about 90 minutes, about 30minutes to about 60 minutes, or about 60 minutes to about 90 minutes.Further, in some embodiments, the duration of tissue separation can betuned by altering one or more of the components of a first and/or secondcomposition described herein. For example, in some embodiments, theduration of tissue separation can be altered based on the identityand/or amount of one or more of a polymerizable material, cross linker,polymerization initiator, and gas foaming agent described herein.

Moreover, in some embodiments, a method described herein furthercomprises removing at least a portion of a first tissue layer from thebody. For example, in some embodiments, a method further comprisesremoving at least a portion of diseased tissue such as cancerous tissueor potentially cancerous tissue. Moreover, removing at least a portionof a first tissue layer, in some embodiments, compriseselectrocauterizing the tissue.

Further, in some embodiments, a method described herein furthercomprises dispensing a drug into a tissue layer from a composition orgel described herein. For example, in some embodiments, a methoddescribed herein further comprises dispensing a drug into tissueremaining after at least a portion of a diseased tissue layer isremoved. Dispensing a drug, in some embodiments, can promote healing ofremaining tissue and/or additional treatment of a tissue layer. In someembodiments, for instance, dispensing a drug promotes mucosal healingand/or regeneration. Moreover, in some embodiments, dispensing a drugcomprises slowly releasing the drug. Slow release of a drug, in someembodiments, provides long-lasting therapeutic effects to one or moretissue layers. For example, in some embodiments, a drug is dispensedover the course of up to 2 weeks. In some embodiments, dispensing a drugcomprises quickly releasing an initial amount of the drug followed byslowly releasing the remainder of the drug. Further, the dispensingprofile of a drug described herein, in some embodiments, can becontrolled by altering one or more of the components of a first and/orsecond composition described herein. For example, in some embodiments,the dispensing profile can be altered based on the identity and/oramount of one or more of a polymerizable material, cross linker, andpolymerization initiator described herein.

In addition, in some embodiments, a method described herein furthercomprises dispensing an imaging agent into a tissue layer from acomposition or gel described herein. Dispensing an imaging agent, insome embodiments, can permit imaging of one or more tissue layersbefore, during, and/or after tissue separation, resection, and/ortreatment.

Moreover, in some embodiments, a method described herein furthercomprises degrading a polymerizable material and/or a polymerizationproduct of a polymerizable material described herein, such as a gel.Degrading, in some embodiments, comprises biodegrading, includingbiodegrading in vivo. Biodegrading a polymerizable material and/or apolymerization product of a polymerizable material, in some embodiments,comprises degrading the polymerizable material and/or polymerizationproduct to non-toxic components which can be cleared from the body byordinary biological processes. In some embodiments, a polymerizablematerial and/or polymerization product completely or substantiallycompletely degrades over the course of about 4 weeks or less.

In another aspect, a method of separating biological tissue comprisesproviding a composition comprising a polymerizable material, disposingthe composition at a first site beneath a first tissue layer,polymerizing the polymerizable material at the first site, andseparating the first tissue layer from a second tissue layer. Thecomposition, in some embodiments, further comprises all componentsrequired to polymerize the polymerizable material at the first site,without the need to heat or irradiate the first site. For example, insome embodiments, the composition comprises one or more components of afirst composition described hereinabove and one or more components of asecond composition described hereinabove. Any components notinconsistent with the objectives of the present invention may be used.Moreover, in some embodiments, the components are selected to achieve adesired polymerization rate such as a slow reaction rate, as describedfurther hereinbelow. In addition, in some embodiments, the methodcomprises one or more additional steps. For example, in someembodiments, the method further comprises maintaining separation of thefirst and second tissue layers for a therapeutically effective period oftime, as described hereinabove. In some embodiments, the method furthercomprises removing at least a portion of the first tissue layer from thebody, as described hereinabove. In some embodiments, the method furthercomprises dispensing a drug and/or an imaging agent into a tissue layerfrom a composition or gel described herein, as described hereinabove. Insome embodiments, the method further comprises degrading thepolymerizable material and/or a polymerization product of thepolymerizable material, such as a gel, as described hereinabove.

FIG. 1 illustrates a method for separating tissue according to oneembodiment described herein. In the embodiment of FIG. 1, first tissuelayer 100 comprises a lesion 200 (FIG. 1A). The lesion 200 issubstantially confined to the superficial mucosal and submucosal layers,which are positioned over second tissue layer 300. Second tissue layer300 comprises healthy muscle tissue. A first composition 400 is disposedat a first site 500 beneath the first tissue layer 100 (FIGS. 1B and1C), causing separation of the first tissue layer 100 from the secondtissue layer 300 (FIG. 1C). In the embodiment of FIG. 1, firstcomposition 400 is an aqueous solution having a viscosity greater thansaline. Further, first composition 400 remains a liquid at the firstsite 500 prior to addition of a second composition 600. When a secondcomposition 600 is disposed at the first site 500 (FIG. 1D), a gel 700is formed (FIG. 1E). In the embodiment of FIG. 1, second composition 600comprises an aqueous solution. Formation of the gel 700 increases theseparation of the first tissue layer 100 from the second tissue layer300. In addition, disposing the second composition 600 at the first site500 produces a gas 800 through reaction of a gas foaming agent (notshown) of the second composition 600 with one or more acid groups of thepolymerizable material (not shown) of the first composition 400 (FIG.1E). Providing a gas 800 results in further separation of the firsttissue layer 100 from the second tissue layer 300 (FIG. 1E).

Turning now to specific steps of methods, methods for separating tissuedescribed herein comprise providing a first composition comprising apolymerizable material. Any polymerizable material not inconsistent withthe objectives of the present invention may be used. For example, insome embodiments, a polymerizable material is monomeric. In someembodiments, a polymerizable material is oligomeric or polymeric.Moreover, in some embodiments, a polymerizable material comprises one ormore olefin moieties, such as a vinyl group. In some embodiments, apolymerizable material comprises one or more carboxyl and/or hydroxylgroups. In some embodiments, a polymerizable material comprises apolymer or oligomer formed from an olefin-containing monomer, such as anunsaturated polyol or polycarboxylic acid. In some embodiments, apolymerizable material comprises a polymer or oligomer formed from apolycarboxylic acid, a polyol, and an olefin-containing monomer. Apolycarboxylic acid, in some embodiments, comprises a dicarboxylic acid.In some embodiments, a polycarboxylic acid comprises a tricarboxylicacid. In some embodiments, a polycarboxylic acid comprises citric acid.A polyol, in some embodiments, comprises an alkane diol, such as anα,ω-alkane diol, including a C2-C12 alkane diol. In some embodiments, apolyol comprises a poly(ethylene glycol). Any poly(ethylene glycol) notinconsistent with the objectives of the present invention may be used.In some embodiments, for instance, a poly(ethylene glycol) has amolecular weight between about 100 and about 5000. An olefin-containingmonomer, in some embodiments, comprises an olefin moiety and one or moreother polymerizable groups, such as one or more alcohol groups, one ormore carboxylic acid groups, or one or more anhydride groups. Forexample, in some embodiments, an olefin-containing monomer comprises anunsaturated polyol or polyacid such as a vinyl-containing diol or avinyl-containing dicarboxylic acid. In some embodiments, the one or moreother polymerizable groups of an olefin-containing monomer are operableto react and form a bond with a hydroxyl group, such as a hydroxyl groupof a polyol described herein. In some embodiments, an olefin-containingmonomer comprises one or more of fumaric acid, itaconic acid,allylmalonic acid, maleic acid, and maleic anhydride.

In some embodiments, a polymerizable material comprises a polymer oroligomer formed from citric acid, a polyol, and maleic acid. In someembodiments, a polymerizable material comprises poly(ethylene glycolmaleate citrate) (PEGMC). In some embodiments, a polymerizable materialcomprises a polymer or oligomer described in Gyawali et al., “Citricacid-derived in situ crosslinkable biodegradable polymers for celldelivery,” Biomaterials 2010, 31, 9092-9105; or United States PatentApplication Publication No. 2011/0124765, the entireties of which arehereby incorporated by reference.

In some embodiments, a polymerizable material is formed from one or moremonomers of Formula (A), one or more monomers of Formula (B) or (B′),and one or more monomers of Formula (C) or Formula (C′):

wherein R₁, R₂, R₃, and R₄ are independently —H, methyl, or ethyl,R₅ and R₆ are independently —H, —OH, —OR₇, methyl, or ethyl,R₇ is methyl or ethyl, andn and m are independently integers ranging from 1 to 100.

Further, the monomers of Formula (A), (B), (B′), (C) and (C′) can beused in any ratio not inconsistent with the objectives of the presentinvention. In addition, altering the ratios of monomers can, in someembodiments, alter the reactivity and/or other properties of thepolymerizable material formed from the monomers. Moreover, in someembodiments, the reactivity and/or other properties of a polymerizablematerial can affect one or more of the in situ polymerization, crosslinking, gel formation, gel time, gel properties, mucosal liftelevation, and/or mucosal lift duration of a method described herein. Insome embodiments, the ratio of monomer (A) to monomer (B) or monomer(B′) is between about 1:10 and about 10:1 or between about 1:5 and about5:1. In some embodiments, the ratio of monomer (A) to monomer (B) ormonomer (B′) is between about 1:4 and about 4:1. In some embodiments,the ratio is about 1:1. Further, in some embodiments, the ratio ofmonomer (A) to monomer (C) or monomer (C′) is between about 1:10 andabout 10:1. In some embodiments, the ratio of monomer (A) to monomer (C)or monomer (C′) is about 1:1.

In some embodiments, a polymerizable material comprises a polymer oroligomer of Formula (I):

wherein R₈ is

R₉ is

x and y are integers independently ranging from 1 to 100; andz is an integer ranging from 1 to 20.

In some embodiments, a polymerizable material described herein has amolecular weight between about 500 and about 50,000. In someembodiments, a polymerizable material has a molecular weight betweenabout 500 and about 20,000, between about 1000 and about 10,000 orbetween about 500 and about 5000.

In addition, in some embodiments of methods described herein, apolymerizable material is biodegradable. A biodegradable polymerizablematerial, in some embodiments, comprises one or more ester bonds.Moreover, in some embodiments, a biodegradable material degrades in vivoto non-toxic components which can be cleared from the body by ordinarybiological processes.

Further, in some embodiments, a polymerizable material described hereinis biocompatible or cytocompatible. A biocompatible or cytocompatiblematerial, in some embodiments, is non-toxic and does not causesubstantial tissue inflammation.

Moreover, in some embodiments, a polymerizable material described hereinis water soluble or water dispersible. In some embodiments, for example,a first composition described herein comprises a polymerizable materialdissolved or substantially dissolved in an aqueous solution. In otherembodiments, a first composition comprises a polymerizable materialsuspended in an aqueous solution. An aqueous solution, in someembodiments, comprises ultrapure water. In other embodiments, an aqueoussolution comprises phosphate buffered saline (PBS).

In addition, a polymerizable material described herein can be present ina first composition in any amount not inconsistent with the objectivesof the present invention. For example, in some embodiments, apolymerizable material is present in a first composition in an amountbetween about 10 weight percent and about 60 weight percent. In someembodiments, a polymerizable material is present in a first compositionin an amount between about 10 weight percent and about 50 weightpercent, between about 10 weight percent and about 40 weight percent,between about 10 weight percent and about 30 weight percent, betweenabout 20 weight percent and about 60 weight percent, or between about 20weight percent and about 40 weight percent.

Further, in some embodiments, a first composition comprises one or morespecies in addition to a polymerizable material. For example, in someembodiments, a first composition further comprises a cross linker. Anycross linker not inconsistent with the objectives of the presentinvention may be used. In some embodiments, for example, a cross linkercomprises one or more olefins or olefinic moieties. In some embodiments,a cross linker comprises an acrylate or polyacrylate, including adiacrylate. In some embodiments, a cross linker comprises one or more of1,3-butanediol diacrylate, 1,6-hexanediol diacrylate, glycerol1,3-diglycerolate diacrylate, di(ethylene glycol) diacrylate,poly(ethylene glycol) diacrylate, poly(propylene glycol) diacrylate, andpropylene glycol glycerolate diacrylate. In some embodiments, a crosslinker comprises a nucleic acid, including DNA or RNA. In someembodiments, a cross linker comprises a “click chemistry” reagent, suchas an azide or an alkyne. In some embodiments, a cross linker comprisesan ionic cross linker.

In addition, a cross linker described herein can be present in a firstcomposition in any amount not inconsistent with the objectives of thepresent invention. For example, in some embodiments, a cross linker ispresent in a first composition in an amount between about 5 weightpercent and about 50 weight percent. In some embodiments, a cross linkeris present in a first composition in an amount between about 5 weightpercent and about 40 weight percent, between about 5 weight percent andabout 30 weight percent, between about 10 weight percent and about 40weight percent, between about 10 weight percent and about 30 weightpercent, or between about 20 weight percent and about 40 weight percent.

Moreover, in some embodiments described herein, a first compositionfurther comprises an imaging agent. Any imaging agent not inconsistentwith the objectives of the present invention may be used. In someembodiments, for example, an imaging agent comprises a radiopaquematerial. A radiopaque material, in some embodiments, comprises bariumor iodine. In some embodiments, an imaging agent comprises a dye, suchas an organic dye. For instance, in some embodiments, an imaging agentcomprises methylene blue. In some embodiments, an imaging agentcomprises a fluorescent dye. In some embodiments, an imaging agentcomprises a fluorescent protein. In some embodiments, an imaging agentcomprises a lanthanide species, such as a lanthanide chelate. In someembodiments, an imaging agent comprises a quantum dot, including a II-VIor III-V quantum dot. Moreover, in some embodiments, an imaging agentcomprises a luminescent oligomer or polymer, including a luminescentoligomer or polymer comprising an alpha-amino acid such as cysteine. Analpha-amino acid, in some embodiments, is disposed in or chemicallybonded to a polymerizable material described herein. For example, insome embodiments, an alpha-amino acid is polymerized or oligomerizedwith one or more other monomers of a polymerizable material describedherein.

An imaging agent described herein can be present in a first compositionin any amount not inconsistent with the objectives of the presentinvention. In some embodiments, for instance, an imaging agent ispresent in a first composition in an amount between about 0.01 mg/mL andabout 100 mg/mL.

In addition, in some embodiments, a first composition further comprisesa drug. Any drug not inconsistent with the objectives of the presentinvention may be used. In some embodiments, for example, a drugcomprises a mucosal protective pharmaceutical or an ulcer healingpharmaceutical. In some embodiments, a drug comprises a prostaglandingeneration promoter. In some embodiments, a drug comprises a proton-pumpinhibitor. In some embodiments, a drug comprises a hemostatic and/oranti-neoplastic composition. In some embodiments, a drug comprisesRebamipide and/or omeprazole.

Moreover, a drug described herein, in some embodiments, is watersoluble. In other embodiments, a drug is disposed in a polymeric micellein the first composition. In some embodiments, a drug described hereinis chemically bonded to a polymerizable material described herein, suchas through one or more covalent bonds. One or more covalent bonds, insome embodiments, comprise bonds between a hydroxyl or carboxyl group ofthe polymerizable material and an appropriate functional group on thedrug, such as an amine group. In some embodiments, a drug is chemicallybonded to a polymerizable material through one or more ionic bonds,electrostatic bonds, or hydrogen bonds.

A drug described herein can be present in a first composition in anyamount not inconsistent with the objectives of the present invention. Insome embodiments, for instance, a drug is present in a first compositionin an amount between about 0.01 mg/mL and about 100 mg/mL. In someembodiments, a drug is present in a first composition in an amountbetween about 0.1 mg/mL and about 10 mg/mL or between about 0.1 mg/mLand about 1 mg/mL.

Further, in embodiments described herein wherein a first compositioncomprises a plurality of components, the plurality of components can bepresent in the first composition in any ratio not inconsistent with theobjectives of the present invention. For example, in some embodiments,the ratio of polymerizable material to cross linker is between about10:1 and about 1:10. In some embodiments, the ratio of polymerizablematerial to cross linker is between about 10:1 and about 1:1, betweenabout 10:1 and about 5:1, between about 5:1 and about 1:5, between about5:1 and about 1:2, between about 5:1 and about 1:1, or between about 2:1and about 1:2. In some embodiments, the ratio of polymerizable materialto cross linker is about 1:1.

In addition, a first composition described herein can have any viscositynot inconsistent with the objectives of the present invention. In someembodiments, for instance, a first composition has a viscosity greaterthan saline solution, such as 0.9% saline solution. In some embodiments,a first composition has a viscosity high enough to minimize migration ofthe first composition from the injection site over the time scale of amethod described herein but low enough to permit injection through anendoscopic needle at an acceptable injection pressure. In someembodiments, a first composition has a viscosity between about 1centipoise (cP) and about 50 cP at 37° C. In some embodiments, a firstcomposition has a viscosity between about 1 cP and about 20 cP, betweenabout 1 cP and about 10 cP, between about 1.5 cP and about 9 cP, betweenabout 2 cP and about 8 cP, or between about 2 cP and about 5 cP at 37°C. Further, in some embodiments, a first composition exhibits aninjection pressure between about 10 psi and about 100 psi when injectedat a rate of 20 mL/min using a 10 mL syringe fitted with a 25-gaugeneedle. In some embodiments, a first composition exhibits an injectionpressure between about 20 psi and about 80 psi, between about 20 psi andabout 60 psi, between about 20 psi and about 50 psi, or between about 20psi and about 30 psi.

Methods for separating tissue described herein also comprise providing asecond composition comprising a polymerization initiator. Anypolymerization initiator not inconsistent with the objectives of thepresent invention may be used. For example, in some embodiments, apolymerization initiator comprises a free radical initiator. In someembodiments, a polymerization initiator comprises a redox initiator. Insome embodiments, a polymerization initiator comprises an oxidizingagent. Further, in some embodiments, a polymerization initiator is watersoluble. In some embodiments, a polymerization initiator comprises ahalide, persulfate, azo compound, or peroxide. In some embodiments, apolymerization initiator comprises an amine, including a diamine. Insome embodiments, a polymerization initiator comprises one or more ofammonium persulfate, potassium persulfate, 4,4′-azobis(4-cyanovalericacid), and 2,2′-azobis(2-methylpropionamidine) dihydrochloride.

Further, in some embodiments, a second composition described hereincomprises a polymerization initiator dissolved or substantiallydissolved in an aqueous solution. An aqueous solution, in someembodiments, comprises ultrapure water. In other embodiments, an aqueoussolution comprises phosphate buffered saline (PBS).

In addition, a polymerization initiator described herein can be presentin a second composition in any amount not inconsistent with theobjectives of the present invention. In some embodiments, for instance,a polymerization initiator is present in a second composition in anamount between about 0.1 weight percent and about 3 weight percent. Insome embodiments, a polymerization initiator is present in a secondcomposition in an amount between about 0.1 weight percent and about 1weight percent, or between about 0.1 weight percent and about 0.5 weightpercent.

Moreover, in some embodiments of methods described herein, a secondcomposition comprises one or more species in addition to apolymerization initiator. For example, in some embodiments, a secondcomposition further comprises a gas foaming agent. Any gas foaming agentnot inconsistent with the objectives of the present invention may beused. For instance, in some embodiments, a gas foaming agent comprisesbicarbonate. A gas foaming agent comprising bicarbonate, in someembodiments, can release carbon dioxide gas when combined with a firstcomposition, such as a first composition comprising an acid.Non-limiting examples of gas foaming agents suitable for use in someembodiments described herein include sodium bicarbonate, potassiumbicarbonate, and ammonium bicarbonate.

A gas foaming agent described herein can be present in a secondcomposition in any amount not inconsistent with the objectives of thepresent invention. For example, in some embodiments, a gas foaming agentis present in the second composition in an amount between about 1 weightpercent and about 20 weight percent. In some embodiments, a gas foamingagent is present in the second composition in an amount between about 1weight percent and about 10 weight percent, between about 1 weightpercent and about 5 weight percent, or between about 5 weight percentand about 10 weight percent.

In some embodiments, a second composition described herein furthercomprises a drug and/or imaging agent. A drug and/or imaging agent of asecond composition can comprise any drug and/or imaging agent describedhereinabove regarding the first composition. Moreover, a drug and/orimaging agent can be present in a second composition in any amount notinconsistent with the objectives of the present invention. For example,in some embodiments, a drug or imaging agent is present in a secondcomposition in an amount between about 0.01 mg/mL and about 100 mg/mL.

Further, a second composition described herein can have any viscositynot inconsistent with the objectives of the present invention. In someembodiments, the viscosity of the second composition is sufficiently lowfor injection of the second composition through an endoscopic needle. Insome embodiments, the viscosity of the second composition issufficiently high to permit the second composition to remain in the areaof the injection site for a time period sufficient to permit crosslinking, polymerization, and/or gelling of the polymerizable material ofa first composition described herein. In some embodiments, a secondcomposition has a viscosity between about 1 cP and about 5 cP, betweenabout 1 cP and about 3 cP, or between about 1 cP and about 2 cP at 37°C.

In embodiments described herein wherein a second composition comprises aplurality of components, the plurality of components can be present inthe second composition in any ratio not inconsistent with the objectivesof the present invention. Further, a second composition described hereincan be provided in any amount not inconsistent with the objectives ofthe present invention, including in any suitable ratio compared to thefirst composition. For example, in some embodiments, the ratio of thefirst composition to the second composition is between about 10:1 andabout 1:10. In some embodiments, the ratio of the first composition tothe second composition is between about 5:1 and about 1:5, between about2:1 and about 1:2, or about 1:1.

Methods described herein also comprise disposing a first composition anda second composition at a first site beneath a first tissue layer. Afirst or second composition can be disposed at the first site in anymanner not inconsistent with the objectives of the present invention. Insome embodiments, for instance, a composition is injected at a firstsite. Moreover, injecting, in some embodiments, comprises injecting witha syringe. In some embodiments, injecting comprises injecting with anendoscopic device, such as an endoscope or endoscopic needle. Further,in some embodiments, a composition such as a first composition isdisposed in direct contact with tissue at the first site.

Methods described herein, in some embodiments, also comprise removing atleast a portion of a first tissue layer from the body. At least aportion of a first tissue layer can be removed in any manner notinconsistent with the objectives of the present invention. In someembodiments, for example, removing is carried out endoscopically,including with an endoscope or other endoscopic device.

Methods described herein, in some embodiments, further comprisedispensing a drug and/or an imaging agent into a tissue layer from acomposition or gel described herein. Dispensing a drug and/or imagingagent can be carried out in any manner not inconsistent with theobjectives of the present invention. In some embodiments, for instance,dispensing comprises permitting slow release of the drug and/or imagingagent via diffusion of the drug and/or imaging agent out of thecomposition or gel. In some embodiments, dispensing comprises releasingvia degradation of the composition or gel, such as biodegradation of thecomposition or gel.

II. Systems for Use in Tissue Separation Applications

In another aspect, systems for use in tissue separation applications aredescribed herein. Tissue separation applications, in some embodiments,include applications requiring the separation of unhealthy tissue suchas tumor tissue from healthy tissue. For example, in some embodiments,tissue separation applications include endoscopic resection applicationssuch as EMR and ESD, including injection-assisted EMR and ESD. In someembodiments, tissue separation applications include separation of theprostate from the rectum during prostate radiation therapy.

In some embodiments, a system for use in tissue separation applicationscomprises a first composition comprising a polymerizable material, asecond composition comprising a polymerization initiator, and anendoscopic device. In some embodiments, the first composition furthercomprises a cross linker. In some embodiments, the second compositionfurther comprises a gas foaming agent. In some embodiments, the firstcomposition and/or the second composition further comprises a drugand/or an imaging agent.

Turning now to specific components of systems, systems for use in tissueseparation applications described herein comprise a first compositioncomprising a polymerizable material. Any polymerizable material notinconsistent with the objectives of the present invention may be used.In some embodiments, a polymerizable material comprises a polymerizablematerial described hereinabove in Section I.

Further, in some embodiments, a first composition described hereincomprises one or more components in addition to a polymerizablematerial. In some embodiments, for instance, a first composition furthercomprises a cross linker. Any cross linker not inconsistent with theobjectives of the present invention may be used. In some embodiments, across linker comprises any cross linker described hereinabove in SectionI. In some embodiments, a first composition further comprises a drug.Any drug not inconsistent with the objectives of the present inventionmay be used. In some embodiments, a drug comprises any drug describedhereinabove in Section I. In some embodiments, a first compositiondescribed herein further comprises an imaging agent. Any imaging agentnot inconsistent with the objectives of the present invention may beused. In some embodiments, an imaging agent comprises any imaging agentdescribed hereinabove in Section I.

Systems described herein also comprise a second composition comprising apolymerization initiator. Any polymerization initiator not inconsistentwith the objectives of the present invention may be used. In someembodiments, a polymerization initiator comprises any polymerizationinitiator described hereinabove in Section I.

Moreover, in some embodiments, a second composition described hereincomprises one or more components in addition to a polymerizationinitiator. For example, in some embodiments, a second compositiondescribed herein further comprises a drug. Any drug not inconsistentwith the objectives of the present invention may be used. In someembodiments, a drug comprises any drug described hereinabove in SectionI. In some embodiments, a second composition described herein furthercomprises an imaging agent. Any imaging agent not inconsistent with theobjectives of the present invention may be used. In some embodiments, animaging agent comprises any imaging agent described hereinabove inSection I.

Systems described herein also comprise an endoscopic device, Anyendoscopic device not inconsistent with the objectives of the presentinvention may be used. In some embodiments, an endoscopic devicecomprises an endoscope. In some embodiments, an endoscopic devicecomprises an endoscopic needle. In some embodiments, an endoscopicdevice comprises a camera or lens.

III. Methods for Displacing Soft Biological Tissue

In another aspect, methods for displacing soft biological tissue aredescribed herein. In some embodiments, a method for displacing softtissue comprises providing a first composition comprising apolymerizable material, providing a second composition comprising apolymerization initiator, disposing the first composition at a firstsite within a first soft tissue, disposing the second composition at thefirst site, polymerizing the polymerizable material at the first site,and displacing the first soft tissue. Displacing a first soft tissue, insome embodiments, comprises reducing wrinkles, such as wrinkles on theskin. In some embodiments, displacing a first soft tissue comprisesincreasing the total volume of a tissue or body part, such as a lip.Moreover, in some embodiments, displacing a first soft tissue comprisesdisplacing the tissue by an amount and for a duration describedhereinabove in Section I regarding the separation of tissue layers.

Turning now to specific steps of methods, methods for displacingbiological tissue described herein comprise providing a firstcomposition comprising a polymerizable material and a second compositioncomprising a polymerization initiator. The first composition and secondcomposition can comprise any first composition and second compositiondescribed hereinabove in Section I, including any polymerizable materialand polymerization initiator described hereinabove in Section I.Similarly, the first and second compositions can be disposed at a firstsite within a first soft tissue in any manner not inconsistent with theobjectives of the present invention, including in a manner describedhereinabove in Section I. Further, the first soft tissue can compriseany soft tissue not inconsistent with the objectives of the presentinvention. In some embodiments, for instance, the first soft tissuecomprises skin or lip tissue. In some embodiments, the first soft tissuecomprises tissue beneath the skin.

IV. Systems for Use in Tissue Displacement Applications

In another aspect, systems for use in tissue displacement applicationsare described herein. Tissue displacement applications, in someembodiments, include cosmetics applications such as anti-wrinkleapplications and lip-plumping applications. In some embodiments, asystem for use in tissue displacement applications comprises a firstcomposition comprising a polymerizable material, a second compositioncomprising a polymerization initiator, and an injection device.

Turning now to specific components of systems, system for use in tissuedisplacement applications described herein comprise a first compositioncomprising a polymerizable material and a second composition comprisinga polymerization initiator. The first composition and second compositioncan comprise any first composition and second composition describedhereinabove in Section I, including any polymerizable material andpolymerization initiator described hereinabove in Section I. Inaddition, the injection device of a system described herein can compriseany injection device not inconsistent with the objectives of the presentinvention. In some embodiments, for example, the injection devicecomprises a syringe.

Some embodiments described herein are further illustrated in thefollowing non-limiting examples.

EXAMPLE 1 PEGMC

A polymerizable material suitable for use in some embodiments describedherein was prepared as follows. Citric acid (0.4 mol, Sigma Aldrich),maleic anhydride (0.6 mol, Sigma Aldrich), and poly(ethylene glycol)(molecular weight 200, 1.0 mol, Sigma Aldrich) were added to a 250-mLround bottom flask equipped with a magnetic stir bar. The mixture wasstirred at 300 rpm for 10 minutes at 160° C. under a continuous flow ofnitrogen to melt the solids. The temperature was then reduced to 140° C.and stirring was continued for another 2 hours. The pressure inside theflask was then reduced to 50 mTorr for an additional 2 hours. Theresulting product was then dissolved in ultrapure water (Millipore,Billerica, Mass.) and purified using a dialysis membrane (500 MW cutoff,Cole-Parmer, Vernon Hills, Ill.). The resulting purified material wasthen collected and lyophilized to produce a purified PEGMC material.

EXAMPLE 2 First Composition

A first composition suitable for use in some embodiments describedherein was prepared as follows. The purified PEGMC material of Example 1(0.2 g/mL water), poly(ethylene glycol) diacrylate (PEGDA, 700 MW, 0.16g/mL water, Sigma Aldrich), and tetramethylethylenediamine (TEMED, 6μL/mL water, Sigma Aldrich) were dissolved in ultrapure water.

The viscosity of the composition was measured using a Brookfield DV-IICone Plate Viscometer (Brookfield, Middleboro, Mass.). A 1-mL sample ofthe composition was placed between a 1.565° cone spindle and plate ofthe viscometer, and the viscosity was measured at 37° C. at 12 rpm.

The maximum injection pressure developed during injection of thiscomposition was measured as follows. A 5-mL sample of the compositionwas loaded into a 10-mL syringe. The syringe was then loaded onto asyringe pump (KD Scientific Model 200, Holliston, Mass.). Next, thesyringe, a digital traceable manometer (Cole-Parmer, Vernon Hills,Ill.), and a 25-gauge, three-foot sclerotherapy needle (US Endoscopy,Mentor, Ohio) were connected to a three-way Luer lock stopcock (Qosina,Edgewood, N.Y.) as illustrated in FIG. 2. The injection rate of thesyringe pump was set at 20 mL/minute and injection was begun. Themaximum pressure value (in psi) was recorded at the time when a steadyforce of embolus of the syringe produced a fluid jet of stable radiusfrom the tip of the sclerotherapy needle.

EXAMPLE 3 Second Composition

A second composition suitable for use in some embodiments describedherein was prepared as follows. Ammonium persulfate (APS) was dissolvedin ultrapure water at 0.25 weight percent. In addition, in someembodiments, 5 weight percent sodium bicarbonate was also dissolved inthe ultrapure water, providing a second composition comprising both apolymerization initiator (APS) and a gas foaming agent (sodiumbicarbonate).

EXAMPLE 4 Gels

A series of gels comprising a cross linked polymerizable materialaccording to some embodiments described herein was formed as follows. Adesired amount of the first composition of Example 2 and a desiredamount of the second composition of Example 3 were combined in a 2:1ratio by volume and allowed to mix by diffusion for various times.

Rheological properties of the gels are determined using multiwaverheology experiments applying multiple frequencies simultaneously inoscillatory experiments with time. In particular, the first and secondcompositions are combined and then immediately transferred to theparallel plate of a rheometer (TA Instrument, ARES-G2, 25 mm plates witha 1.9 mm gap at 37° C.). An oscillatory small strain γ(t) was imposed onthe sample:

$\gamma = {\sum\limits_{i = 1}^{m}{\gamma_{i}{\sin\left( {\omega_{i}t} \right)}}}$where m is the number of the superimposed harmonics, and γ_(i) and ω_(i)denote the amplitude and the frequency of the i^(th) harmonic,respectively. The frequencies of the harmonics are ω_(n)=nω_(f) with thefundamental frequency ω_(f). Further, ω_(f)=10 rad/s (n=1, 5, 10) andγ_(i)=2%. Data collection is started immediately after the sample isloaded and continues for 1000 s. The gel point is identified as thecross-over of the viscous and elastic moduli. Frequency sweepexperiments from 0.1 to 100 rad/s are conducted on samples. The strainamplitude in frequency sweep measurements is 10% to remain within theregion of viscoelasticity. Viscoelastic properties are characterized bythe complex shear modulus:G*=G′+iG″and complex shear viscosity:η*=G*//iω

To determine the overall expansion volumes caused by the formation ofthe gels, 500 μL of the first composition and 250 μL of the secondcomposition were combined in a 3 mL glass vial and permitted to mix bydiffusion. Photographic images were recorded at 0, 0.25, 0.50, 1, 2, 3,4, 5, 10, 20 and 30 minutes after combination. The expansion volume attime t was determined using Image J Analysis Software and the followingequation:Expansion volume(%)=100×(V _(t) −V ₀)V ₀,where V_(t) is the total volume at time t and V₀ is the initial totalvolume. FIG. 3 illustrates the results for a series of gels formed froma series of first compositions having differing concentrations of PEGMC(10 weight percent, 15 weight percent, and 20 weight percent).

The mechanical properties of gels were determined as follows. Mechanicaltests were carried out on cylindrical gel samples in an unconfined state3 mm in diameter and 10 mm in height using an MTS Insight II mechanicaltester fitted with a 10 N load cell (MTS, Eden Prairie, Minn.). The load(N) versus compression (%) was recorded using Testworks 4 Software at acrosshead speed of 1 mm/minute at various strain levels. The stress at50% strain (compressive peak stress) was recorded along with the initialmodulus (0-10% strain). Specifically, the initial modulus was calculatedfrom the initial (0-10% strain) slope of the compressive stress vs.strain curve.

The electrical properties of gels are determined as follows. Electricalimpedance is measured with a potentiostat electroimpedance spectrometer(Gamry Instruments, Pennsylvania) and insulation tipped knife (OlympusOptical, Tokyo, Japan) using 0.01 N KCl as a reference solution.Material resistance is calculated from the following equation:ρ=1/σ=R _(S) /K _(cell),where ρ is resistance (Ω cm), σ is the conductivity (mS/cm), R_(S) iselectrical impedance (a), and K_(cell) is the cell constant.

EXAMPLE 5 Dispensing a Drug

The release profile of a drug from a series of gels formed according tosome embodiments described herein was determined as follows. Rebamipide(1 mM) was mixed with a series of first compositions produced accordingto Example 2. The series of first compositions included PEGMCpolymerizable materials produced with citric acid to maleic anhydridemonomer ratios of 0.4, 0.6, and 0.8. The drug-loaded first compositionswere mixed with a series of second compositions produced according toExample 3 to provide a series of gels comprising Rebamipide. Thedrug-loaded gels were placed in glass vials and allowed to incubate inphosphate buffered saline (37° C., pH 7.4) for 2 weeks. Aliquots (0.2mL) were taken from the supernatant of each vial at various intervals,and the amount of Rebamipide present in the supernatant was determinedby high performance liquid chromatography (HPLC, Waters, Milford,Mass.). FIG. 4 illustrates the results.

EXAMPLE 6 Ex Vivo Studies

Methods of separating tissue according to some embodiments describedherein were carried out as follows. Biological tissues were separated exvivo. The upper thirds of porcine stomachs were used for ex vivo studiesdue to their resemblance to the human stomach in thickness andhistology. Porcine stomach samples were obtained immediately aftersacrifice (Columbia Packing, Dallas, Tex.). Each porcine stomachspecimen was cut into 5 cm×5 cm pieces and fixed onto a flat corkboardusing steel pins. Using a 2.5 mL syringe equipped with a 25-gaugeneedle, 1 mL of a first composition produced according to Example 2 and1 mL of a second composition produced according to Example 3 wereinjected tangentially into the submucosa of the specimens through themucosal surface. Each of the first and second compositions alsocontained methylene blue (0.5 mL methylene blue/10 mL composition) forvisualization. Photographs of the mucosal elevation were recorded at 0,1, 2, 3, 4, 5, 10, 15, 20 and 30 minutes immediately followinginjection. Mucosal elevation heights were determined quantitatively fromthe photographs using Image J Analysis Software. All injections wereperformed within 1 hour after the animals' death, and all tests wereperformed at a constant temperature of 37° C. For comparison, aqueoussolutions of saline (0.9%) and sodium hyaluronate (SH, 0.4%) were alsoinjected into porcine stomach specimens as described above. FIG. 5 showsa series of photographs of the mucosal elevation heights for injectionsusing (A) saline, (B) SH, and (C) first and second compositionsdescribed herein at 1, 5, 15, and 30 minutes after injection. The dataof FIG. 5C was produced using a first composition comprising 30 weightpercent PEGMC. The scale bars are 5 mm. All the submucosal cushionscreated according to a method described herein were more durable thanthose created with saline or SH. FIG. 6 shows a plot of the mucosalelevation height as a function of time for the injections of FIG. 5.FIG. 7 shows a plot of the mucosal elevation height as a function oftime for injections of saline, SH, and first and second compositionsdescribed herein, wherein the first composition included 20 weightpercent PEGMC and the second composition included sodium bicarbonate.

EXAMPLE 7 In Vivo Studies

Methods of separating tissue according to some embodiments describedherein were carried out as follows. Four in vivo EMR procedures wereperformed using a live porcine stomach model. Veterinary care for theanimal subjects was provided by the animal lab at the University ofMississippi Medical Center (UMMC) and maintained under the guidelines ofthe UMMC Institutional Animal Care and Use Committee according tocurrent NIH guidelines. All surgical manipulations were performed underanesthesia using sterile technique. All of the guidelines as outlined bythe American Association for the Accreditation of Laboratory Animal Carewere followed to ensure that discomfort, distress, pain, and injury werelimited to that which was unavoidable in the conduct of scientificallysound research. All pigs were euthanized by administration of a lethaldose of sodium pentobarbital as per recommendations of the AmericanVeterinary Medical Association.

First and second compositions produced according to Examples 2 and 3,respectively, were injected using the same 25-gauge catheter injectionneedle. The first composition was easily injected and was able to createan adequate submucosal cushion. The second composition was injected intothe same injection site without any clogging inside the delivery tool.Five minutes following injection of the second composition, an “en bloc”resection of the elevated mucosa was performed with a hook-knife andpolypectomy snare and recorded with endoscopic photographs. The en blocresection of the elevated mucosa revealed a soft biodegradable gelunderneath the mucosa, providing protection for the underlying musclelayer from electrocautery damage. The presence of the gel did notcomplicate the resection procedure or require any changes to theelectrocautery settings.

Various embodiments of the invention have been described in fulfillmentof the various objectives of the invention. It should be recognized thatthese embodiments are merely illustrative of the principles of thepresent invention. Numerous modifications and adaptations thereof willbe readily apparent to those skilled in the art without departing fromthe spirit and scope of the invention.

That which is claimed is:
 1. A method for separating tissue comprising:providing a first composition comprising a polymerizable material;providing a second composition comprising a polymerization initiator;disposing the first composition at a first site beneath a first softtissue layer, the first site comprising an interfacial region betweenthe first tissue layer and an adjacent second soft tissue layer;disposing the second composition at the first site; and polymerizing thepolymerizable material at the first site, thereby separating the firsttissue layer from the second tissue layer and forming a gap between thetissue layers of about 1 mm to about 10 mm, the separation of the firstand second tissue layers being at least partially caused by thepolymerization of the polymerizable material at the first site, whereinthe polymerizable material comprises a polymer or oligomer of Formula(I):

wherein R₈ is

R₉ is

x and y are integers independently ranging from 1 to 100; and z is aninteger ranging from 1 to
 20. 2. The method of claim 1, wherein thefirst composition further comprises a cross linker.
 3. The method ofclaim 2, wherein the cross linker comprises an acrylate or polyacrylate.4. The method of claim 1, wherein the first composition furthercomprises a drug.
 5. The method of claim 1, wherein the polymerizationinitiator comprises a free radical initiator or redox initiator.
 6. Themethod of claim 1, wherein the second composition further comprises agas foaming agent.
 7. The method of claim 6, wherein the gas foamingagent comprises bicarbonate.
 8. The method of claim 1, whereinpolymerizing the polymerizable material comprises forming a gel.
 9. Themethod of claim 1, wherein separating the first tissue layer from thesecond tissue layer comprises providing a gas between the first andsecond tissue layers.
 10. The method of claim 1 further comprisingremoving at least a portion of the first tissue layer from the bodyfollowing the polymerization of the polymerizable material at the firstsite.
 11. The method of claim 1 further comprising dispensing a druginto a tissue layer from the first or second composition.
 12. The methodof claim 1 further comprising biodegrading the polymerizable materialand/or a polymerization product formed from the polymerizable material.13. A method for separating tissue comprising: providing a compositioncomprising a polymerizable material; disposing the composition at afirst site beneath a first soft tissue layer, the first site comprisingan interfacial region between the first tissue layer and an adjacentsecond soft tissue layer; and polymerizing the polymerizable material atthe first site, thereby separating the first tissue layer from thesecond tissue layer and forming a gap between the tissue layers of about1 mm to about 10 mm, the separation of the first and second tissuelayers being at least partially caused by the polymerization of thepolymerizable material at the first site, wherein the polymerizablematerial comprises a polymer or oligomer of Formula (I):

wherein R₈ is

R₉ is

x and y are integers independently ranging from 1 to 100; and z is aninteger ranging from 1 to 20.